Fallstaff OD/"Fat Mastered" boost (this is something ... sort of new)

[midwayfair]

I made this.

This might be a nice change for people who like Rangemasters but just can't get them to work in their chain.

Background:
I started building Rangemasters in February, just after I started build effects pedals. I love the sound of most old germanium effects, but I use a compressor as my "base" tone, and an orange squeezer is pretty much always on in my rig. This makes a treble boost just a unity volume sparky thing for my setup, because they'll amplify the high end content of the Orange Squeezer into the stratosphere. It can get pretty harsh in a stock setting above unity volume and also the volume knob seemed to behave differently - percieved unity volume when the compressor was on was much lower on the dial than when the compressor was off.

I started digging around for ways to balance the sound. The easiest was to use one of the input cap mods or add an input cap tone knob (which I did - and I like the pedal that came out of that just fine). But I thought it would be much more interesting to work up something that sounded the same whether a buffer or other pedal was on in front of the circuit or not.

Adding a buffer ...
After fiddling around with tons of input/output camp values and adding a few different small capacitors across the volume knob, I remembered that one of the great things about Skreddy's Lunar Module and Screwdriver is that they took an effect (the Fuzz Face) that normally hates having pedals in front of and made it sound good by adding an extra input stage.

So I went back to the breadboard and built AMZ's simple buffer. Harsh city with a treble booster. But I tweaked some values, removed the redundant circuitry (no need for an output cap in the buffer section, for instance), and added a treble cut. A little more tweaking and the boost soon behaved the same when it was just guitar > boost > amp as when it was guitar > comp > boost > amp.

My "color" knob circuit
There was one last thing. While tweaking every possible value and component I could in this circuit, I discovered that adding a diode clipping section could add bass content. I finally settled on a germanium diode and 1N914, both facing toward ground, which added the most bass. Originally I planned on making it a switch that also added a cap from the volume knob to ground to cut the highs and make this a bass booster, but I found that I could get a lot more interesting sounds by putting it on a pot. I've made some notes in the PDF about tweaking the values of this circuit.

I can't think of another pedal that uses a tone control quite like this. It adds some distortion and bass from the diodes, but it also cuts the highs at the same time and so the distortion evens out some. That's why I'm calling it a "color" knob - it's more than just a tone stack.

Here's what I ended up with:
[EDIT EDIT: This is fixed now. EDIT: Very important! The transistor icons are backwards; I will fix them and replace the picture as soon as I can.]


Here's what it sounds like with lots of notes:

And here's a PDF with the schematic and some mod notes:
http://midwayfair.files.wordpress.com/2012/04/falstaff-od2.pdf

This is not exactly a treble booster as I built it, although it sounds similar. I chose values that provided a more of a full range boost; you could use smaller input caps and it'll function more like a classic Rangemaster.

The color knob can be added to any existing Rangemaster, by the way, but I wouldn't suggest adding the buffer input stage if you're using a normal-sized input cap. It'll be much brighter.

I've got some good pics but I forgot to pull them off the camera. Doh! I'll post them in the thread after I get home.

Pics!

[joegagan]

wow, way to bring it! this is refreshing when compared to newbie posts, you made a nice entry there.

quick note, your schem shows the trans as pnp with the arrow direction.

will dig a little further into your post, and am looking forward to whatever you come up with in the future.

[midwayfair]

wow, way to bring it! this is refreshing when compared to newbie posts, you made a nice entry there.

quick note, your schem shows the trans as pnp with the arrow direction.

will dig a little further into your post, and am looking forward to whatever you come up with in the future.

Thanks! I was worried about that - I will flip them when I get home. (I had the arrow where the tick mark was on my transistors.)

[slacker]

Sounds great, nice playing as well.

It's not the transistor symbols that need flipping it's just the arrow, you're using the PNP symbol where the arrow points towards the transistor. In the NPN symbol the arrow points away from the transistor.

There's a picture here that should help http://www.kpsec.freeuk.com/components/tran.htm

[Bill Mountain]

This looks like a cool project.  The only thing I notice is that with the Ge diode in there I don't believe the Si one will ever clip.

[midwayfair]

This looks like a cool project.  The only thing I notice is that with the Ge diode in there I don't believe the Si one will ever clip.

It definitely sounded different (less bass) without the silicon in there. It also sounded different with a different silicon diode (just more distortion). It also sounds different if I turn the Ge diode around.

I'm not saying you're wrong, but I don't know enough to say what exactly happens. It may be that the Si isn't adding any clipping, but it definitely did *something.*

[Bill Mountain]

This looks like a cool project.  The only thing I notice is that with the Ge diode in there I don't believe the Si one will ever clip.

It definitely sounded different (less bass) without the silicon in there. It also sounded different with a different silicon diode (just more distortion). It also sounds different if I turn the Ge diode around.

I'm not saying you're wrong, but I don't know enough to say what exactly happens. It may be that the Si isn't adding any clipping, but it definitely did *something.*

Fair enough.  The Ge diode will clip at something around .3 volts and there won't be anything left for the Si to clip (which usually clips around .7 volts).  Now to be honest, in my own experiments it has never been as simple as the math suggests but that is the rule of thumb and why I even suggested it with seeing your pedal in person.

Either way it looks and sounds great.

[midwayfair]

This looks like a cool project.  The only thing I notice is that with the Ge diode in there I don't believe the Si one will ever clip.

It definitely sounded different (less bass) without the silicon in there. It also sounded different with a different silicon diode (just more distortion). It also sounds different if I turn the Ge diode around.

I'm not saying you're wrong, but I don't know enough to say what exactly happens. It may be that the Si isn't adding any clipping, but it definitely did *something.*

Fair enough.  The Ge diode will clip at something around .3 volts and there won't be anything left for the Si to clip (which usually clips around .7 volts).  Now to be honest, in my own experiments it has never been as simple as the math suggests but that is the rule of thumb and why I even suggested it with seeing your pedal in person.

Either way it looks and sounds great.

It's good to know and I appreciate it - so thank you. I don't pretend to be an expert by any means.

I have to use my ears because Numbers and I have a history of fistfights and drunken brawls, and they haven't forgiven me for what I did to them in 8th grade. It would make a lot of my life easier if I were better at math. It would certainly help tune circuits quicker.

[midwayfair]

The new build document is in Google Docs, so it's always up to date, and it contains a new etch layout:
https://docs.google.com/document/d/1033QEzKtTQJ0B3pTqJyp3mo-y4V7ErbM35hi3phTJLI/edit

The schematic in the build document contains some improvements. I'd post it here, but the picture is huge and the forum won't let me resize it.

[Ben N]

Sorry about the necro... Jon, I PMed you about this.

[midwayfair]

Sorry about the necro... Jon, I PMed you about this.

I don't seem to have any new PMs.

[Ben N]

Hmmmm 
OK, check again. sorry 'bout that.